NT® Strip electrodes

The high-performance submerged-arc strip and RES-strip weld-surfacing processes are applied predominantly for cladding over large areas for protecting new components against corrosion and wear, or for regenerating damaged components. The basic principle of the submerged-arc strip weld-surfacing process is well known: With the generation of electric arcs, the continuously fed strip electrodes as well as the base metal undergo fusion. This process occurs in the co-called cavern underneath a powder cover. RES cladding differs from the submerged-arc strip process because of the different means of heat input. The heat necessary for fusing the substrate material and the strip electrode is generated by the Joule effect in this process, rather than by an electric arc. The current flows through the strip and through a layer of electrically conductive slag and thus initiates the welding process by resistance heating (slag temperature: about 2300 °C).

Because of their economic advantages, the ease of handling, the high degree of automation, and low cost of acquisition for the necessary equipment, these weld-surfacing processes have become well established long ago wherever claddings must be applied to large surface areas. Such claddings are required for protecting plant components against corrosion, for instance, in the chemical industry, in vessel and apparatus construction, as well as in process technology. For applications of this kind, a wide range of welding fillers from alloy group 9, as specified in DIN 8555, are available for use with these processes. These materials are corrosion-, acid-, and heat-resistant Cr Ni steels for applying protective claddings by weld surfacing. Strip electrodes are available up to a width of 180 mm; as a rule, the thickness ranges between 0.5 and 1 mm.

Sintered strip electrodes provide an alternative to solid strips. Special-purpose alloys with dimensions up to 80 mm in width and from 0.5 to 1 mm in thickness can also be prepared in small lots within a short time.